Cause Analysis on Stress Corrosion Cracking of 0Cr18Ni9 Stainless Steel Heat Exchange Tubes

After a tube-in-sheet heat exchanger being put into use for less than 2 months, cracking happened at the inlet end of the heat exchange tubes. By means of macro analysis, chemical composition analysis, water quality analysis, metallographic analysis, fracture analysis, energy spectrum analysis and so on, the cracking property and reasons of the heat exchange tubes were analyzed. The results show the cracking of the heat exchange tubes was stress corrosion cracking which caused by the combined action of high content of chloride ion in the circulating cooling water and stress corrosion sensitive temperature of the inlet end of the heat exchange tubes. Finally, measures of adopting post weld heat treatment and strengthening circulating cooling water treatment were proposed.